Paraffin Deposition and Rheological Evaluation of High Wax Content Altamont Crude Oils

Abstract

Abstract The Altamont area in Utah produces one of the highest wax content crudes anywhere in the world. These high pour point and hard to handle crude oils are an even tougher problem because of their location in a geographical area subject to very low ambient temperatures. Millions of dollars are spent each year heating these crudes in order to expedite their production and transportation. Crude oil samples from the area have been tested using a variety of techniques. Paraffin deposition, viscosity, cloud point, pour point, yield values, wax extraction and GLC tests have been conducted in order to characterize the crude oil samples. The effects of various chemical additives were then analyzed using the same tests. The effective paraffin inhibitors not only reduced the quantity of wax deposited, but dramatic shifts in molecular weight range and configuration were also apparent. GLC data indicates that effective chemical structures all reduced the quantity of C 40-50 molecular weight waxes contained in the resulting paraffin deposits. Introduction The precipitation of paraffin waxes from crude oil is a commonly observed phenomenon in the production of petroleum products. A variety of mechanical, production of petroleum products. A variety of mechanical, thermal and chemical treatments have evolved over the years to alleviate the problems associated with these deposition and pumping problems. If the wax content of the crude oil is low to moderate (0–10%) these problems are periodic and handled on an "as needed" basis. With wax contents above 10% these crudes experience severe deposition and flow problems necessitating constant treatment to ensure continued production. Many of these problem crudes display pour points above 30 degrees problem crudes display pour points above 30 degrees C (86 degrees F) such as Minas, Udang, Kuda Laut, Dickinson, Bombay High, Daqing and Handil. Particularly severe production problems due to high wax Particularly severe production problems due to high wax content crudes are encountered with the Wasatch crude produced in the Altamont, Utah area of the United States. Various methods have been designed to treat high wax content crudes including heating/cooling/ shear cycles, water emulsions, crystal modification chemical and heat. The use of chemical additives for pour point reduction and paraffin deposition inhibition is receiving considerable paraffin deposition inhibition is receiving considerable attention as new and improved formulations are developed. The combination of pour point, viscosity and yield value data has been determined to effectively describe a crude oil's rheological propertieswith and without chemical additives. Paraffin deposition testing using a variety of static cold spots, cold section loops, and dynamic probes has resulted in improved screening probes has resulted in improved screening techniques for paraffin inhibitors. The use of analytical instruments such as GLC, mass spec and GPC has led to information on the chemical composition and distribution of the high molecular weight fractions contained in the crude oil. All of the above techniques were used to study the Wasatch crude oil in order to identify active crystal modification chemicals for future field trial purposes. Wasatch Crude Oil Wasatch crude oil is produced in the Altamont area by flowing, beam pump, gas lift and power water methods. The wells are around 3050 m(10,000 ft.) deep with bottom hole temperatures of approximately 93 degrees C (200 degrees F). Severe paraffin deposition takes place in the upper 2000 m (6,560 ft.) and the flowlines and tanks are heated. While the crude is all classified as Wasatch it varies considerably in physical appearance. Three crude samples were tested which covered the range of properties observed in the field. Wax analysis, properties observed in the field. Wax analysis, pour point and cloud point were determined pour point and cloud point were determined by standard techniques. Table #1 is a summary of the physical properties. P. 321